Plasma treatment apparatus and plasma treatment method

ABSTRACT

According to one embodiment, there is provided a plasma treatment apparatus including an electrode, a first power supply circuit, a plasma generating unit, a second power supply circuit, a sensing unit, and a control unit. The electrode is arranged inside a treatment chamber. On the electrode, a substrate to be treated is placed. The first power supply circuit supplies power to the electrode. The plasma generating unit generates plasma in a space separated from the electrode inside the treatment chamber. The second power supply circuit supplies power to the plasma generating unit. The sensing unit senses a parameter output from the first power supply circuit. The control unit controls power supplied from the second power supply circuit so that the parameter sensed by the sensing unit becomes close to or substantially equal to a target value.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2010-150094, filed on Jun. 30, 2010; and the prior Japanese Patent Application No. 2010-185134, filed on Aug. 20, 2010; the entire contents of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to a plasma treatment apparatus and a plasma treatment method.

BACKGROUND

In recent years, with the progress in miniaturization of semiconductor devices, there is a demand for improvement of processing precision in a processing technique of semiconductor devices. In particular, in an etching technique using a plasma treatment apparatus, such as a reactive ion etching (RIE) apparatus, a variation in processing dimension or etching amount between (a plurality of) different plasma treatment apparatuses of the same model becomes important so as not to be negligible in light of necessary processing precision even under the same processing condition.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing the configuration of a plasma treatment apparatus according to a first embodiment;

FIG. 2 is a flowchart showing an operation of a control device in the first embodiment;

FIG. 3 is a flowchart showing an operation of a control device in a second embodiment;

FIG. 4 is a diagram showing the configuration of a plasma treatment apparatus according to a modification of the first embodiment and the second embodiment;

FIGS. 5A and 5B are diagrams showing an operation of a plasma treatment apparatus according to a comparative example;

FIG. 6 is a diagram showing an operation of a plasma treatment apparatus according to a comparative example;

FIG. 7 is a diagram showing the configuration of a plasma treatment apparatus according to a third embodiment;

FIG. 8 is a diagram showing the configuration of a correcting unit in the third embodiment;

FIG. 9 is a flowchart showing a method of manufacturing a semiconductor device using the plasma treatment apparatus according to the third embodiment;

FIG. 10 is a diagram showing the configuration of a plasma treatment apparatus according to a fourth embodiment;

FIG. 11 is a diagram showing the configuration of a correcting unit in the fourth embodiment;

FIG. 12 is a diagram showing the data structure of a storage unit in the fourth embodiment;

FIG. 13 is a flowchart showing a method of manufacturing a semiconductor device using the plasma treatment apparatus according to the fourth embodiment;

FIG. 14 is a diagram showing the configuration of a correcting unit in a fifth embodiment;

FIG. 15 is a diagram showing the data structure of a storage unit in the fifth embodiment;

FIG. 16 is a flowchart showing a method of manufacturing a semiconductor device using a plasma treatment apparatus according to the fifth embodiment;

FIG. 17 is a diagram showing the configuration of a plasma treatment apparatus according to a sixth embodiment;

FIG. 18 is a diagram showing the data structure of a storage unit in the sixth embodiment;

FIG. 19 is a flowchart showing a method of manufacturing a semiconductor device using the plasma treatment apparatus according to the sixth embodiment; and

FIG. 20 is a diagram showing an operation of a plasma treatment apparatus according to a comparative example.

DETAILED DESCRIPTION

In general, according to one embodiment, there is provided a plasma treatment apparatus including an electrode, a first power supply circuit, a plasma generating unit, a second power supply circuit, a sensing unit, and a control unit. The electrode is arranged inside a treatment chamber. On the electrode, a substrate to be treated is placed. The first power supply circuit supplies power to the electrode. The plasma generating unit generates plasma in a space separated from the electrode inside the treatment chamber. The second power supply circuit supplies power to the plasma generating unit. The sensing unit senses a parameter output from the first power supply circuit. The control unit controls power supplied from the second power supply circuit so that the parameter sensed by the sensing unit becomes close to or substantially equal to a target value.

Exemplary embodiments of a plasma treatment apparatus will be explained below in detail with reference to the accompanying drawings. The present invention is not limited to the following embodiments.

First Embodiment

A plasma treatment apparatus 1 according to a first embodiment will be described with reference to FIG. 1. FIG. 1 is a diagram showing the schematic configuration of the plasma treatment apparatus 1 according to the first embodiment.

The plasma treatment apparatus 1 includes a treatment chamber 50, an electrode 10, a power supply circuit (first power supply circuit) 20, a plasma generating unit 30, a power supply circuit (second power supply circuit) 40, and a control device 60.

The treatment chamber 50 is a chamber which is used to generate plasma PL therein, and is formed of a treatment container 2. The treatment container 2 is configured such that a treatment gas can be supplied from a supply source (not shown) to the treatment chamber 50 and the treatment gas after treatment process can be exhausted from the treatment chamber 50 to an exhaust device (not shown).

The electrode 10 is arranged on the bottom surface of the treatment chamber 50 so as to be insulated from the treatment container 2 through an insulating material (not shown). A substrate WF to be treated (for example, a semiconductor substrate) is placed on the electrode 10. The electrode 10 is formed of, for example, metal.

The power supply circuit 20 generates radio-frequency power and supplies the radio-frequency power to the electrode 10. The radio-frequency power is power which is used to accelerate ions (for example, F⁺, CF3⁺, or the like), which are generated from the treatment gas along with radicals when the plasma PL is generated in the treatment chamber 50, toward the electrode 10 (toward the substrate WF to be treated). The frequency of the radio-frequency power is, for example, 13.56 MHz.

The power supply circuit 20 has a radio-frequency power supply 22 and a matching circuit 21.

The radio-frequency power supply 22 has a generating unit 22 a, a sensing unit 22 b, and a feedback control unit 22 c. The generating unit 22 a generates radio-frequency power. The sensing unit 22 b senses power (radio-frequency power) Pb generated by the generating unit 22 a. The feedback control unit 22 c controls power generated by the generating unit 22 a in accordance with the sensing result of the sensing unit 22 b so that the power Pb sensed by the sensing unit 22 b is substantially identical to set power

Pbset. The details of the sensing unit 22 b and the feedback control unit 22 c will be described below.

The matching circuit 21 has, for example, a variable capacitor and a variable coil. The matching circuit 21 performs impedance adjustment (impedance matching) using the variable capacitor and the variable coil so that impedance on the radio-frequency power supply 22 side with respect to the matching circuit 21 matches with impedance on the electrode 10 side with respect to the matching circuit 21.

The plasma generating unit 30 generates the plasma PL in a space 51 separated from the electrode 10 inside the treatment chamber 50. Specifically, the plasma generating unit 30 has an antenna coil 31 and a dielectric wall 32. The antenna coil 31 generates electromagnetic waves (high-frequency magnetic field) using the radio-frequency power supplied from the power supply circuit 40. The electromagnetic waves generated by the antenna coil 31 pass through the dielectric wall 32 and are introduced into the space 51 of the treatment chamber 50. In the space 51 of the treatment chamber 50, the treatment gas is discharged to generate the plasma PL, which includes ions (for example, F⁺, CF3⁺, or the like) and radicals (for example, F*, O*, or the like). The dielectric wall 32 also serves as the upper wall of the treatment container 2.

The power supply circuit 40 generates radio-frequency power and supplies the radio-frequency power to the plasma generating unit 30. The radio-frequency power is power which is used when the plasma generating unit 30 generates plasma PL in the treatment chamber 50. The frequency of the radio-frequency power is, for example, 13.56 MHz.

The power supply circuit 40 has a matching circuit 41 and a radio-frequency power supply 42. The radio-frequency power supply 42 generates radio-frequency power and supplies the radio-frequency power to the antenna coil 31. The matching circuit 41 has, for example, a variable capacitor and a variable coil. The matching circuit 41 performs impedance adjustment (impedance matching) using the variable capacitor and the variable coil so that impedance on the radio-frequency power supply 42 side with respect to the matching circuit 41 matches with impedance on the antenna coil 31 side with respect to the matching circuit 41.

The control device 60 controls the plasma treatment apparatus 1. Specifically, the control device 60 has an input unit 65, a probe (sensing unit) 63, and a feedback control circuit (control unit) 64.

The set power Pbset and a set voltage Vbset are input from a user to the input unit 65 in the control device 60. Alternatively, the input unit 65 receives the set power Pbset and the set voltage Vbset from a host computer or another plasma treatment apparatus through a communication line. The set voltage Vbset and the set power Vbset are respectively determined in advance as a common value between different plasma treatment apparatuses. The input unit 65 supplies the value of the set power Pbset to the feedback control unit 22 c in the radio-frequency power supply 22, and supplies the value of the set voltage Vbset to the feedback control circuit 64.

The sensing unit 22 b in the radio-frequency power supply 22 senses the power (radio-frequency power) Pb generated by the generating unit 22 a. The sensing unit 22 b supplies the value of the sensed power Pb to the feedback control unit 22 c.

The feedback control unit 22 c in the radio-frequency power supply 22 receives the value of the set power Pbset from the input unit 65 and holds the value of the set power Pbset as a target value. If the value of the sensed power Pb is received from the sensing unit 22 b, the feedback control unit 22 c compares the power Pb with the set power Pbset, and controls power generated by the generating unit 22 a so that the power Pb sensed by the sensing unit 22 b is substantially identical to the set power Pbset. Specifically, when the sensed power Pb is higher than the set power Pbset, the feedback control unit 22 c controls the generating unit 22 a to decrease power to be generated. When the sensed power Pb is lower than the set power Pbset, the feedback control unit 22 c controls the generating unit 22 a to increase power to be generated.

The probe 63 in the control device 60 senses a voltage (parameter) Vb output from the power supply circuit 20. For example, the probe 63 senses the voltage on a node N1 between the electrode 10 and the power supply circuit 20 as the voltage Vb output from the power supply circuit 20. The probe 63 supplies the value of the sensed voltage Vb to the feedback control circuit 64.

The feedback control circuit 64 in the control device 60 receives the value of a set voltage Vbset from the input unit 65 and holds the value of the set voltage Vbset as a target value. If the value of the sensed voltage Vb is received from the probe 63, the feedback control circuit 64 compares the voltage Vb with the set voltage Vbset, and controls power supplied from the power supply circuit 40 so that the voltage Vb sensed by the probe 63 becomes close to or substantially equal to the set voltage Vbset. Specifically, when the sensed voltage Vb is higher than the set voltage Vbset, the feedback control circuit 64 controls the radio-frequency power supply 42 in the power supply circuit 40 to increase power to be generated. When the sensed voltage Vb is lower than the set voltage Vbset, the feedback control circuit 64 controls the radio-frequency power supply 42 in the power supply circuit 40 to decrease power to be generated.

For example, when power output from the power supply circuit 20 is substantially identical to the set power Pbset, if the voltage Vb sensed by the probe 63 is higher than the set voltage Vbset, this equivalently means that an ion current formed by ions accelerated inside the treatment chamber 50 is smaller than a target value corresponding to the set voltage Vbset. Thus, when the sensed voltage Vb is higher than the set voltage Vbset, if power supplied from the power supply circuit 40 to the plasma generating unit 30 increases, and the density of plasma generated inside the treatment chamber 50 increases, the ion current (the density of ions to be accelerated) can become close to or substantially equal to the target value.

Alternatively, for example, when power output from the power supply circuit 20 is substantially identical to the set power Pbset, if the voltage Vb sensed by the probe 63 is lower than the set voltage Vbset, this equivalently means that an ion current formed by ions accelerated inside the treatment chamber 50 is greater than a target value corresponding to the set voltage Vbset. Thus, when the sensed voltage Vb is lower than the set voltage Vbset, if power supplied from the power supply circuit 40 to the plasma generating unit 30 decreases, and the density of plasma generated inside the treatment chamber 50 decreases, the ion current (the density of ions to be accelerated) can become close to or substantially equal to the target value.

Next, the operation of the control device 60 will be described with reference to FIG. 2. FIG. 2 is a flowchart showing the operation of the control device 60.

In Step S1, the substrate WF to be treated (for example, a semiconductor substrate) is placed on the electrode 10 inside the treatment chamber 50. The power supply circuit 20 generates radio-frequency power and supplies the radio-frequency power to the electrode 10. Along with this, the power supply circuit 40 generates radio-frequency power and supplies the radio-frequency power to the plasma generating unit 30. The plasma generating unit 30 generates the plasma PL in the space 51 separated from the electrode 10 inside the treatment chamber 50. Specifically, the radio-frequency power supply 42 generates radio-frequency power and supplies the radio-frequency power to the antenna coil 31. The antenna coil 31 generates electromagnetic waves (high-frequency magnetic field) using the supplied radio-frequency power. The electromagnetic waves generated by the antenna coil 31 pass through the dielectric wall 32 and are introduced into the space 51 of the treatment chamber 50. In the space 51 of the treatment chamber 50, a treatment gas is discharged to generate the plasma PL, which includes ions (for example, F⁺, CF3⁺, or the like) and radicals (for example, F*, O*, or the like).

In Step S2, the probe 63 senses the voltage Vb output from the power supply circuit 20. For example, the probe 63 senses the voltage on the node N1 between the electrode 10 and the power supply circuit 20 as the voltage Vb output from the power supply circuit 20. The probe 63 supplies the value of the sensed voltage (bias-side voltage) Vb to the feedback control circuit 64.

In Step S3, the feedback control circuit 64 receives the value of the set voltage Vbset from the input unit 65 and holds the value of the set voltage Vbset as a target value. If the value of the sensed voltage Vb is received from the probe 63, the feedback control circuit 64 compares the voltage (bias-side voltage) Vb with the set voltage (target value) Vbset. When the sensed voltage Vb is lower than the set voltage Vbset, the feedback control circuit 64 progresses the process to Step S4. When the sensed voltage Vb is higher than the set voltage Vbset, the feedback control circuit 64 progresses the process to Step S5. When the sensed voltage Vb is substantially identical to the set voltage Vbset, the process ends.

In Step S4, the feedback control circuit 64 controls the radio-frequency power supply 42 in the power supply circuit 40 to decrease power to be generated.

In Step S5, the feedback control circuit 64 controls the radio-frequency power supply 42 in the power supply circuit 40 to increase power to be generated.

In this way, the processing of Steps S2 to S5 (the operation of the probe 63 to sense the voltage Vb output from the power supply circuit 20 and the control operation of the feedback control circuit 64) is repeatedly performed until the bias-side voltage Vb is substantially identical to the set voltage (target value) Vbset. Though not shown, the operation of the sensing unit 22 b to sense the power Pb generated by the generating unit 22 a in the power supply circuit 20 and the control operation of the feedback control unit 22 c are performed in parallel with the processing of Steps S2 to S5.

A case, as a comparative example, where the control device 60 has no feedback control circuit 64 is taken into consideration. In this case, the control operation of the feedback control circuit 64 in the control device 60 is not performed, and the operation of the sensing unit 22 b to sense the power Pb generated by the generating unit 22 a in the power supply circuit 20 and the control operation of the feedback control unit 22 c are performed. Thus, even when power (bias-side power) output from the power supply circuit 20 can be substantially equalized between a plurality of different plasma treatment apparatuses of the same model, the voltage (bias-side voltage) output from the power supply circuit 20 tends to vary between a plurality of different plasma treatment apparatuses of the same model. For example, as shown in FIG. 5A, although the bias-side power is equalized as 500 W between a plurality of different plasma treatment apparatuses A1 to A3 of the same model, the bias-side voltage varies to 300 V, 350 V, and 250 V. Accordingly, since processing is performed with an etching rate deviated from a user's request, the processing precision of each plasma treatment apparatus tends to be degraded. Simultaneously, a variation in the processing dimension or etching amount between (a plurality of) different plasma treatment apparatuses of the same model tends to be not negligible with respect to necessary processing precision even under the same processing condition.

Alternatively, there is taken into consideration a case, as a comparative example, where the power supply circuit 20 has no sensing unit 22 b and feedback control unit 22 c, and the feedback control circuit 64 controls power supplied from the power supply circuit 20 (power generated by the generating unit 22 a of the radio-frequency power supply 22) so that the voltage Vb sensed by the probe 63 is identical to the set voltage Vbset. In this case, in the control device 60, the operation of the probe 63 to sense the voltage Vb output from the power supply circuit 20 and the operation of the feedback control circuit 64 to control the power supply circuit 20 are performed. Thus, even when the voltage (bias-side voltage) output from the power supply circuit 20 can be substantially equalized between a plurality of different plasma treatment apparatuses of the same model, power (bias-side power) output from the power supply circuit 20 tends to vary between a plurality of different plasma treatment apparatuses of the same model. For example, as shown in FIG. 5B, although the bias-side voltage is substantially equalized as 300 V between a plurality of different plasma treatment apparatuses A4 to A6 of the same model, the bias-side power varies to 500 W, 430 W, and 570 W. Accordingly, since processing is performed with an etching rate deviated from a user's request, the processing precision of each plasma treatment apparatus tends to be degraded. Simultaneously, a variation in the processing dimension or etching amount between (a plurality of) different plasma treatment apparatuses of the same model tends to be not negligible with respect to necessary processing precision even under the same processing condition.

For example, FIG. 6 shows the evaluation result of an etching rate of plasma treatment for a plurality of plasma treatment apparatuses in which the bias-side power Pb varies in a state where the bias-side voltage is constant. From FIG. 6, it can be understood that the etching rate significantly varies between the plasma treatment apparatuses in which the bias-side power Pb is different.

In contrast, in the first embodiment, the control device 60 has the feedback control circuit 64, and the control operation of the feedback control unit 22 c in the power supply circuit 20 and the control operation of the feedback control circuit 64 in the control device 60 are performed in parallel in a mutually independent form. That is, the feedback control unit 22 c controls power generated by the generating unit 22 a so that the power Pb sensed by the sensing unit 22 b is substantially identical to the set power Pbset. Thus, power (bias-side power) output from the power supply circuit 20 can be substantially identical to the set power Pbset determined in advance as a common value between different plasma treatment apparatuses. The feedback control circuit 64 controls power supplied from the power supply circuit 40 so that the voltage (parameter) Vb sensed by the probe 63 is substantially identical to the set voltage (target value) Vbset. Thus, the voltage (bias-side voltage) output from the power supply circuit 20 can be substantially identical to the set voltage Vbset determined in advance as a common value between different plasma treatment apparatuses. As a result, processing can be performed with an etching rate based on a user's request, that is, with an etching rate corresponding to the set power Pbset and the set voltage (target value) Vbset, thereby improving the processing precision of each plasma treatment apparatus. Simultaneously, both the bias-side voltage and the bias-side power can be substantially equalized between different plasma treatment apparatuses, thereby reducing a variation in the processing dimension or etching amount between different plasma treatment apparatuses.

Alternatively, a case, as a comparative example, where the probe 63 senses power (for example, power on a node N2) output from the power supply circuit 40, not the voltage output from the power supply circuit 20, is taken into consideration. In this case, the feedback control circuit 64 controls power supplied from the power supply circuit 40 so that power (power for plasma generation) sensed by the probe 63 is substantially identical to a predetermined target value. At this time, the assembling state or characteristic of a part (the antenna coil 31, the dielectric wall 32, or the like) in the plasma generating unit 30 varies between different plasma treatment apparatuses. For this reason, even when power (power for plasma generation) output from the power supply circuit 40 can be substantially equalized between a plurality of different plasma treatment apparatuses of the same model, the density of plasma generated inside the treatment chamber 50 tends to vary between a plurality of different plasma treatment apparatuses of the same model. Accordingly, since processing is performed with an etching rate deviated from a user's request, the processing precision of each plasma treatment apparatus tends to be degraded. Simultaneously, it becomes difficult to reduce a variation in the processing dimension or etching amount between different plasma treatment apparatuses.

In contrast, in the first embodiment, the probe 63 senses the voltage output from the power supply circuit 20. Thus, the feedback control circuit 64 can control power supplied from the power supply circuit 40 so that the voltage Vb sensed by the probe 63 is substantially identical to the set voltage Vbset. As a result, processing can be performed with an etching rate based on a user's request, thereby improving the processing precision of each plasma treatment apparatus. Simultaneously, it is possible to reduce a variation in the processing dimension or etching amount between different plasma treatment apparatuses.

In the first embodiment, when the voltage Vb sensed by the probe 63 is higher than the set voltage Vbset, the feedback control circuit 64 controls the radio-frequency power supply 42 in the power supply circuit 40 to increase power to be generated. Thus, (as a result of the control operation of the feedback control unit 22 c), if power output from the power supply circuit 20 is substantially identical to the set power Pbset, power supplied from the power supply circuit 40 to the plasma generating unit 30 increases so as to increase the density of plasma to be generated inside the treatment chamber 50 and to put the ion current (the density of ions to be accelerated) close to or substantially equal to a target value. Alternatively, when the voltage Vb sensed by the probe 63 is lower than the set voltage Vbset, the feedback control circuit 64 controls the radio-frequency power supply 42 in the power supply circuit 40 to decrease power to be generated. Thus, (as a result of the control operation of the feedback control unit 22 c), if power output from the power supply circuit 20 is substantially identical to the set power Pbset, power supplied from the power supply circuit 40 to the plasma generating unit 30 decreases so as to decrease the density of plasma to be generated inside the treatment chamber 50 and to put the ion current (the density of ions to be accelerated) close to or substantially equal to a target value. That is, while a voltage for accelerating ions inside the treatment chamber 50 is substantially identical to a target value, the density of ions to be accelerated inside the treatment chamber 50 can be substantially identical to a target value.

It should be noted that the control operation of the feedback control unit 22 c or the control operation of the feedback control circuit 64 may be performed at the time of initial setting before processing (etching) is performed, may be performed during processing (etching) in addition to the initial setting, may be continuously performed for a time from the initial setting, or may be constantly performed from the initial setting. In this case, it is possible to reduce a time-dependent variation in the processing dimension or etching amount between different plasma treatment apparatuses occurred according to time from the initial setting.

The radio-frequency power supply 22 may further have an input unit 22 d. At this time, the set power Pbset may be input to the input unit 22 d in the radio-frequency power supply 22, not the input unit 65 in the control device 60. In this case, the input unit 22 d in the radio-frequency power supply 22 supplies the value of the set power Pbset to the feedback control unit 22 c, and the feedback control unit 22 c receives the value of the set power Pbset from the input unit 22 d and holds the value of the set power Pbset as a target value.

The control operation of the feedback control unit 22 c or the control operation of the feedback control circuit 64 may be at least partially realized by software, instead of being realized by hardware (circuit).

Second Embodiment

Next, a plasma treatment apparatus 1 according to a second embodiment will be described. Hereinafter, description will be provided focusing on differences from the first embodiment.

In the control device 60 of the plasma treatment apparatus 1 according to the second embodiment, a user inputs set power Pbset and a set current Ibset to the input unit 65. Alternatively, the input unit 65 receives the set power Pbset and the set current Ibset from a host computer or another plasma treatment apparatus through a communication line. The set power Pbset and the set current Ibset are respectively determined in advance as a common value between different plasma treatment apparatuses.

The input unit 65 supplies the value of the set power Pbset to the feedback control unit 22 c in the power supply circuit 20, and supplies the value of the set current Ibset to the feedback control circuit 64.

The sensing unit 22 b in the power supply circuit 20 senses power Pb generated by the generating unit 22 a. The sensing unit 22 b supplies the value of the sensed power Pb to the feedback control unit 22 c.

The feedback control unit 22 c receives the value of the set power Pbset from the input unit 65 and holds the value of the set power Pbset as a target value. If the value of the sensed power Pb is received from the sensing unit 22 b, the feedback control unit 22 c compares the power Pb with the set power Pbset, and controls power generated by the generating unit 22 a so that the power Pb sensed by the sensing unit 22 b is substantially identical to the set power Pbset.

The probe 63 senses a current (parameter) Ib output from the power supply circuit 20. For example, the probe 63 senses a current flowing in the node N1 between the electrode 10 and the power supply circuit 20 (for example, a current in which the direction from the power supply circuit 20 to the electrode 10 is positive) as the current Ib output from the power supply circuit 20. The probe 63 supplies the value of the sensed current Ib to the feedback control circuit 64.

The feedback control circuit 64 receives the value of the set current Ibset from the input unit 65 and holds the value of the set current Ibset as a target value. If the value of the sensed current Ib is received from the probe 63, the feedback control circuit 64 compares the current Ib with the set current Ibset, and controls power supplied from the power supply circuit 40 so that the current Ib sensed by the probe 63 becomes close to or substantially equal to the set current Ibset. Specifically, when the sensed current Ib is greater than the set current Ibset, the feedback control circuit 64 controls the radio-frequency power supply 42 in the power supply circuit 40 to decrease power to be generated. When the sensed current Ib is smaller than the set current Ibset, the feedback control circuit 64 controls the radio-frequency power supply 42 in the power supply circuit 40 to increase power to be generated.

In the plasma treatment apparatus 1 according to the second embodiment, as shown in FIG. 3, the operation of the control device 60 is different from the first embodiment.

In Step S22, the probe 63 senses the current (parameter) Ib output from the power supply circuit 20. For example, the probe 63 senses the current flowing in the node N1 between the electrode 10 and the power supply circuit 20 as the current Ib output from the power supply circuit 20. The probe 63 supplies the value of the sensed current (bias-side current) Ib to the feedback control circuit 64.

In Step S23, the feedback control circuit 64 receives the value of the set current Ibset from the input unit 65 and holds the value of the set current Ibset as a target value. If the value of the sensed current Ib is received from the probe 63, the feedback control circuit 64 compares the current (bias-side current) Ib with the set current (target value) Ibset. When the sensed current Ib is smaller than the set current Ibset, the feedback control circuit 64 progresses the process to Step S24. When the sensed current Ib is greater than the set current Ibset, the process progresses to Step S25. When the sensed current Ib is substantially identical to the set current Ibset, the process ends.

In Step S24, the feedback control circuit 64 controls the radio-frequency power supply 42 in the power supply circuit 40 to increase power to be generated.

In Step S25, the feedback control circuit 64 controls the radio-frequency power supply 42 in the power supply circuit 40 to decrease power to be generated.

In this way, the processing of Steps S22 to S25 (the operation of the probe 63 to sense the current Ib output from the power supply circuit 20 and the control operation of the feedback control circuit 64) is repeatedly performed until the bias-side current Ib is substantially identical to the set current (target value) Ibset. Though not shown, the operation of the sensing unit 22 b to sense the power Pb generated by the generating unit 22 a in the power supply circuit 20 and the control operation of the feedback control unit 22 c are performed in parallel with the processing of Steps S22 to S25.

As described above, in the second embodiment, when the current Ib sensed by the probe 63 is greater than the set current Ibset, the feedback control circuit 64 controls the radio-frequency power supply 42 in the power supply circuit 40 to decrease power to be generated. Thus, power supplied from the power supply circuit 40 to the plasma generating unit 30 decreases so as to decrease the density of plasma to be generated inside the treatment chamber 50 and to put the ion current (the density of ions to be accelerated) close to or substantially equal to a target value. Alternatively, when the current Ib sensed by the probe 63 is smaller than the set current Ibset, the feedback control circuit 64 controls the radio-frequency power supply 42 in the power supply circuit 40 to increase power to be generated. Thus, power supplied from the power supply circuit 40 to the plasma generating unit 30 increases so as to increase the density of plasma to be generated inside the treatment chamber 50 and to put the ion current (the density of ions to be accelerated) close to or substantially equal to a target value. That is, in the second embodiment, while power for accelerating ions inside the treatment chamber 50 is substantially identical to a target value, the density of ions to be accelerated inside the treatment chamber 50 can be substantially identical to a target value.

It should be noted that, although in the first and second embodiments, a case has been described where a plasma treatment apparatus is an inductive coupling plasma (ICP) RIE apparatus, a plasma treatment apparatus is not limited to the ICP RIE apparatus. For example, a plasma treatment apparatus may be an electron cycrotron resonance (ECR) RIE apparatus or a two-frequency parallel flat plate (capacitive coupling) RIE apparatus. When the plasma treatment apparatus 100 is a two-frequency parallel flat plate (capacitive coupling) RIE apparatus, as shown in FIG. 4, a plasma generating unit 130 has an upper electrode 131 which is arranged to face the electrode 10 inside the treatment chamber 50, instead of the antenna coil 31 and the dielectric wall 32.

Alternatively, a plasma treatment apparatus may be an apparatus which has a three or more-frequency power supply (a radio-frequency power supply having three or more different frequencies). In this case, a parameter output from a low-frequency-side power supply circuit may be sensed, and power supplied from a power supply circuit having a higher frequency than the low-frequency-side power supply circuit in the three or more-frequency power supply may be controlled so that the sensed parameter is substantially identical to a predetermined target value.

Third Embodiment

A plasma treatment apparatus 200 according to a third embodiment will be described with reference to FIG. 7. FIG. 7 is a diagram showing the schematic configuration of the plasma treatment apparatus 200 according to the third embodiment. Hereinafter, description will be provided focusing on differences from the first embodiment.

The plasma treatment apparatus 200 includes a power supply circuit 220, a plasma generating unit 280, and a detecting unit 290.

The power supply circuit 220 generates radio-frequency power and supplies the radio-frequency power to the electrode 10. The radio-frequency power is power which is used to accelerate ions (for example, F⁺, CF3⁺, or the like) generated from a treatment gas along with radicals when plasma PL is generated inside the treatment chamber 50 toward the electrode 10 (the substrate WF to be treated). The frequency of the radio-frequency power is, for example, 13.56 MHz. The internal configuration of the power supply circuit 220 will be described below.

The plasma generating unit 280 generates the plasma PL in the space 51 separated from the electrode 10 inside the treatment chamber 50. Specifically, the plasma generating unit 280 has a radio-frequency power supply 281, a matching box 284, an antenna coil 282, and a dielectric wall 283. The radio-frequency power supply 281 generates radio-frequency power and supplies the radio-frequency power to the antenna coil 282. The matching box 284 has, for example, a variable capacitor and a variable coil. The matching box 284 performs impedance adjustment (impedance matching) using the variable capacitor and the variable coil so that impedance on the radio-frequency power supply 281 side with respect to the matching box 284 matches with impedance on the antenna coil 282 side with respect to the matching box 284. The antenna coil 282 generates electromagnetic waves (high-frequency magnetic field) using the supplied radio-frequency power in a state where impedance matching is performed. The electromagnetic waves generated by the antenna coil 282 pass through the dielectric wall 283 and are introduced into the space 51 of the treatment chamber 50. In the space 51 of the treatment chamber 50, the treatment gas is discharged to generate the plasma PL, and ions (for example, F⁺, CF3⁺, or the like) are generated from the treatment gas along with radicals. The dielectric wall 283 also serves as the upper wall of the treatment container.

The detecting unit 290 detects a bias voltage Vb as a difference between a potential Vp1 of the plasma PL generated by the plasma generating unit 280 and a potential Ve of the electrode 10, to which power is supplied from the power supply circuit 220.

Specifically, the detecting unit 290 has a detection terminal 291 which extends to the space 51 of the treatment chamber 50, and a detection terminal 292 which is electrically connected to the electrode 10. The detecting unit 290 detects the potential Vp1 of the plasma PL through the detection terminal 291, and detects the potential Ve of the electrode 10 through the detection terminal 292. The detecting unit 290 obtains the bias voltage Vb, for example, by the following expression.

Vb=Vp1−Ve

The detecting unit 290 supplies the bias voltage Vb detected in the above-described manner to the power supply circuit 220.

Next, the internal configuration of the power supply circuit 220 will be described with reference to FIG. 7.

The power supply circuit 220 has a main unit 240 and a correcting unit 230. The main unit 240 generates power to be supplied to the electrode 10. Specifically, the main unit 240 has a radio-frequency power supply 243, a matching box 242, and a blocking capacitor 241. The radio-frequency power supply 243 generates radio-frequency power. The matching box 242 has, for example, a variable capacitor and a variable coil. The matching box 242 performs impedance adjustment (impedance matching) using the variable capacitor and the variable coil so that impedance on the radio-frequency power supply 243 side with respect to the matching box 242 matches with impedance on the blocking capacitor 241 side with respect to the matching box 242.

The blocking capacitor 241 supplies a high-frequency component of the radio-frequency power supplied from the radio-frequency power supply 243 to the electrode 10 in a state where impedance matching is performed. Thus, the electrode 10 is negatively charged in a state where the plasma PL is positively charged, and ions (for example, F⁺, CF3⁺, or the like) are accelerated toward the electrode 10 (toward the substrate WF to be treated) by the potential difference of both of them, that is, the bias voltage Vb.

The correcting unit 230 receives a signal representing the bias voltage Vb detected by the detecting unit 290 from the detecting unit 290. The correcting unit 230 compensates for the capacitance of the main unit 240 to correct the capacitance value of the power supply circuit 220 so that the bias voltage Vb represented by the signal becomes close to or substantially equal to a target value Vt. The target value Vt is a value which is set in advance in accordance with a predetermined processing condition (gas type, gas pressure, or the like) for an object to be treated and is a common value between plasma treatment apparatuses. A feedback operation which includes the operation of the detecting unit 290 to detect the bias voltage Vb and the operation of the correcting unit 230 to correct the capacitance value of the power supply circuit 220 is repeatedly performed, so that the bias voltage Vb is adjusted to be substantially identical to the target value Vt. Thus, the plasma treatment apparatus 200 processes (for example, etches) the substrate WF to be treated in a state where the bias voltage Vb detected by the detecting unit 290 is substantially identical to the target value Vt.

Next, the internal configuration of the correcting unit 230 will be described with reference to FIG. 8. FIG. 8 is a diagram showing the internal configuration of the correcting unit 230.

The correcting unit 230 has a variable-capacitance unit 235, a comparing unit 233, and a changing unit 234.

The variable-capacitance unit 235 is configured to change the capacitance value thereof in accordance with a received control signal. The comparing unit 233 receives a signal representing the bias voltage Vb detected by the detecting unit 290 from the detecting unit 290. In the comparing unit 233, the target value Vt is set in advance. The comparing unit 233 compares the bias voltage Vb represented by the signal received from the detecting unit 290 with the target value Vt, and supplies the comparison result to the changing unit 234. The changing unit 234 changes the capacitance value of the variable-capacitance unit 235 in accordance with the supplied comparison result.

Specifically, the variable-capacitance unit 235 has a variable-capacitance element (first variable-capacitance element) 231 and a variable-capacitance element (second variable-capacitance element) 232. The variable-capacitance element 231 is connected in series between the electrode 10 and the main unit 240. For example, the variable-capacitance element 231 is configured such that an electrode 231 a thereof is electrically connected to the electrode 10, and an electrode 231 b thereof is electrically connected to the main unit 240. The variable-capacitance element 232 is connected in parallel with the variable-capacitance element 231 between the main unit 240 and the electrode 10. For example, the variable-capacitance element 232 is configured such that an electrode 232 a thereof is electrically connected to the electrode 10 and the electrode 231 a, and an electrode 232 b thereof is connected to the ground voltage. Since one end of the main unit 240 is connected to the ground voltage, the variable-capacitance element 232 is equivalently connected in parallel with the main unit 240 with respect to the electrode 10.

When the comparison result of the comparing unit 233 shows that the bias voltage Vb represented by the signal is higher than the target value Vt, the changing unit 234 performs at least an operation to increase the capacitance value of the variable-capacitance element 232. Thus, since the capacitance value of the variable-capacitance element 232 connected in parallel with the main unit 240 increases, the bias voltage Vb decreases. That is, the capacitance value of the power supply circuit 220 is corrected so that the bias voltage Vb becomes close to or substantially equal to the target value Vt. The changing unit 234 may further perform an operation to decrease the capacitance value of the variable-capacitance element 231.

When the comparison result of the comparing unit 233 shows that the bias voltage Vb represented by the signal is lower than the target value Vt, the changing unit 234 performs at least an operation to increase the capacitance value of the variable-capacitance element 231. Thus, since the capacitance value of the variable-capacitance element 231 connected in series with the main unit 240 increases, the bias voltage Vb increases. That is, the capacitance value of the power supply circuit 220 is corrected so that the bias voltage Vb becomes close to or substantially equal to the target value Vt. The changing unit 234 may further perform an operation to decrease the capacitance value of the variable-capacitance element 232.

In this way, the changing unit 234 changes at least one of the capacitance value of the variable-capacitance element 231 and the capacitance value of the variable-capacitance element 232 in accordance with the comparison result of the comparing unit 233 so that the bias voltage Vb detected by the detecting unit 290 becomes close to or substantially equal to the target value Vt.

Next, a method of manufacturing a semiconductor device using the plasma treatment apparatus 200 according to the third embodiment will be described with reference to FIG. 9. FIG. 9 is a flowchart showing a method of manufacturing a semiconductor device using the plasma treatment apparatus 200.

In Step S31, the substrate WF to be treated (for example, a semiconductor substrate) is placed on the electrode 10 inside the treatment chamber 50.

In Step S32, the power supply circuit 220 generates radio-frequency power and supplies the radio-frequency power to the electrode 10. Along with this, the plasma generating unit 280 generates the plasma PL in the space 51 separated from the electrode 10 inside the treatment chamber 50. Specifically, the radio-frequency power supply 281 generates radio-frequency power and supplies the radio-frequency power to the antenna coil 282. The antenna coil 282 generates electromagnetic waves (high-frequency magnetic field) using the supplied radio-frequency power. The electromagnetic waves generated by the antenna coil 282 pass through the dielectric wall 283 and are introduced into the space 51 of the treatment chamber 50. In the space 51 of the treatment chamber 50, the treatment gas is discharged to generate the plasma PL, and ions (for example, F⁺, CF3⁺, or the like) are generated from the treatment gas along with radicals.

In Step S33, the detecting unit 290 detects the bias voltage Vb as the difference between the potential Vp1 of the plasma PL generated by the plasma generating unit 280 and the potential Ve of the electrode 10, to which power is supplied from the power supply circuit 220.

Specifically, the detecting unit 290 detects the potential Vp1 of plasma PL through the detection terminal 291, and detects the potential Ve of the electrode 10 through the detection terminal 292. The detecting unit 290 obtains the bias voltage Vb, for example, by the following expression.

Vb=Vp1−Ve

The detecting unit 290 supplies the bias voltage Vb detected in the above-described manner to the power supply circuit 220.

In Step S34, the comparing unit 233 of the power supply circuit 220 receives the signal representing the bias voltage Vb detected by the detecting unit 290 from the detecting unit 290. In the comparing unit 233, the target value Vt is set in advance. The comparing unit 233 compares the bias voltage Vb represented by the signal received from the detecting unit 290 with the target value Vt, and supplies the comparison result to the changing unit 234. The changing unit 234 determines whether or not the bias voltage Vb detected by the detecting unit 290 is substantially identical to the target value Vt in accordance with the supplied comparison result. For example, if a difference between the bias voltage Vb and the target value Vt is out of a predetermined allowable range, the changing unit 234 determines that the bias voltage Vb is not substantially identical to the target value Vt. If the difference between the bias voltage Vb and the target value Vt falls within a predetermined allowable range, the changing unit 234 determines that the bias voltage Vb is substantially identical to the target value Vt. When the bias voltage Vb is not substantially identical to the target value Vt (‘No’ in Step S34), the changing unit 234 progresses the process to Step S35. When the bias voltage Vb is substantially identical to the target value Vt (‘Yes’ in Step S34), the process progresses to Step S36.

In Step S35, the changing unit 234 of the power supply circuit 220 changes at least one of the capacitance value of the variable-capacitance element 231 and the capacitance value of the variable-capacitance element 232 in accordance with the supplied comparison result so that the bias voltage Vb detected by the detecting unit 290 becomes close to or substantially equal to the target value Vt.

That is, when the comparison result of the comparing unit 233 shows that the bias voltage Vb represented by the signal is higher than the target value Vt, the changing unit 234 performs at least an operation to increase the capacitance value of the variable-capacitance element 232. Thus, since the capacitance value of the variable-capacitance element 232 connected in parallel with the main unit 240 increases, the bias voltage Vb decreases. That is, the capacitance value of the power supply circuit 220 is corrected so that the bias voltage Vb becomes close to or substantially equal to the target value Vt. The changing unit 234 may further perform an operation to decrease the capacitance value of the variable-capacitance element 231.

When the comparison result of the comparing unit 233 shows that the bias voltage Vb represented by the signal is lower than the target value Vt, the changing unit 234 performs at least an operation to increase the capacitance value of the variable-capacitance element 231. Thus, since the capacitance value of the variable-capacitance element 231 connected in series with the main unit 240 increases, the bias voltage Vb increases. That is, the capacitance value of the power supply circuit 220 is corrected so that the bias voltage Vb becomes close to or substantially equal to the target value Vt. The changing unit 234 may further perform an operation to decrease the capacitance value of the variable-capacitance element 232.

In this way, the processing of Steps S33 to S35 is repeatedly performed until the bias voltage Vb is substantially identical to the target value Vt. The impedance matching by the matching box 242 may be performed each time the correction processing of Step S35 is performed.

In Step S36, the changing unit 234 supplies a signal representing the bias voltage Vb being substantially identical to the target value Vt to a controller (not shown). Accordingly, the controller is switched from the condition for a correction operation to the condition for a processing operation and controls the plasma generating unit 280. Therefore, the plasma treatment apparatus 200 processes (for example, etches) the substrate WF to be treated in a state where the bias voltage Vb detected by the detecting unit 290 is substantially identical to the target value Vt.

Herein, there is taken into consideration a case, as a comparative example, where Steps S33 to S35 in the method of manufacturing a semiconductor device using the plasma treatment apparatus 200 are not performed. In this case, parasitic capacitance in the power supply circuit 220 varies between a plurality of different plasma treatment apparatuses of the same model. For this reason, the bias voltage Vb as the difference between the potential Vp1 of the plasma PL generated by the plasma generating unit 280 and the potential Ve of the electrode 10, to which power is supplied from the power supply circuit 220, tends to vary between different plasma treatment apparatuses. For example, FIG. 20 shows the evaluation result of the bias voltage Vb for a plurality of different plasma treatment apparatuses in a state where the processing of Steps S33 to S35 is not performed after Steps S31 and S32 are performed. From FIG. 20, it can be understood that the bias voltage Vb significantly varies between different plasma treatment apparatuses.

In contrast, in the third embodiment, Steps S33 to S35 are repeatedly performed after Steps S31 and S32 are performed. That is, the processing is repeatedly performed for detecting the bias voltage Vb (Step S33), and when the detected bias voltage Vb is not substantially identical to the target value Vt (‘No’ in Step S34), for correcting the capacitance value of the power supply circuit 220 so that the detected bias voltage Vb is substantially identical to the target value Vt (Step S35). Thus, when the detected bias voltage Vb is substantially identical to the target value Vt (‘Yes’ in Step S34), the plasma treatment apparatus 200 processes the substrate WF to be treated in a state where the bias voltage Vb detected by the detecting unit 290 is substantially identical to the target value Vt (a common value between different plasma treatment apparatuses) (Step S36). As a result, processing can be performed in a state where the bias voltage Vb is substantially equalized to the target value Vt which is common to different plasma treatment apparatuses, thereby reducing a variation in the processing dimension between different plasma treatment apparatuses.

In particular, the correcting unit 230 of the power supply circuit 220 has the variable-capacitance element 231 which is connected in series with the main unit 240 with respect to the electrode 10, and the variable-capacitance element 232 which is connected in parallel with the main unit 240 with respect to the electrode 10. Thus, in Step S35, when the bias voltage Vb is higher or lower than the target value Vt, the capacitance value of the power supply circuit 220 can be corrected so that the bias voltage Vb becomes close to or substantially equal to the target value

Vt.

Alternatively, a case, as a comparative example, where the power supply circuit 220 has no correcting unit 230 is taken into consideration. In this case, as described above, parasitic capacitance in the power supply circuit 220 varies between different plasma treatment apparatuses. For this reason, the bias voltage Vb tends to vary between different plasma treatment apparatuses.

In contrast, in the third embodiment, the power supply circuit 220 has the correcting unit 230. The correcting unit 230 compensates for the capacitance value of the main unit 240 to correct the capacitance value of the power supply circuit 220 so that the bias voltage Vb detected by the detecting unit 290 is substantially identical to the target value Vt (the common value between different plasma treatment apparatuses). Therefore, the plasma treatment apparatus 200 can perform processing in a state where the bias voltage Vb is substantially identical to the target value Vt, thereby reducing a variation in the processing dimension between different plasma treatment apparatuses.

Alternatively, a case, as a comparative example, where the plasma treatment apparatus 200 has no detecting unit 290 is taken into consideration. In this case, the correcting unit 230 cannot recognize the value of the bias voltage Vb, making it difficult to perform correction so that the bias voltage Vb is substantially identical to the target value Vt. Accordingly, it becomes difficult to reduce a variation in the processing dimension between different plasma treatment apparatuses.

Alternatively, a case, as a comparative example, where the plasma treatment apparatus 200 has no detecting unit 290, and has a second detecting unit which detects the capacitance value of the main unit 240 is taken into consideration. In this case, in the plasma treatment apparatus 200, since there are many parameters which should be controlled, the correlation between the capacitance value of the main unit 240 and the bias voltage Vb tends to vary between different plasma treatment apparatuses. For this reason, even when the capacitance value of the main unit 240 detected by the second detecting unit is received, the correcting unit 230 cannot recognize the value of the bias voltage Vb, making it difficult to perform correction so that the bias voltage Vb is substantially identical to the target value Vt. Accordingly, it becomes difficult to reduce a variation in the processing dimension between different plasma treatment apparatuses.

Alternatively, a case, as a comparative example, where the plasma treatment apparatus 200 has no detecting unit 290, and has a third detecting unit which detects the reactance value of the correcting unit 230 is taken into consideration. In this case, in the plasma treatment apparatus 200, since there are many parameters which should be controlled, the correlation between the reactance value of the correcting unit 230 and the bias voltage Vb tends to vary between different plasma treatment apparatuses. For this reason, even when the reactance value of the correcting unit 230 detected by the third detecting unit is received, the correcting unit 230 cannot recognize the value of the bias voltage Vb, making it difficult to perform correction so that the bias voltage Vb is substantially identical to the target value Vt. Accordingly, it becomes difficult to reduce a variation in the processing dimension between different plasma treatment apparatuses.

In contrast, in the third embodiment, the plasma treatment apparatus 200 includes the detecting unit 290. The detecting unit 290 detects the bias voltage Vb. Thus, the correcting unit 230 can recognize the value of the bias voltage Vb, making it possible to perform correction so that the bias voltage Vb is substantially identical to the target value Vt. As a result, it is possible to reduce a variation in the processing dimension between different plasma treatment apparatuses.

In particular, the detecting unit 290 has the detection terminal 291 which extends to the space 51 of the treatment chamber 50, and the detection terminal 292 which is electrically connected to the electrode 10. Thus, the detecting unit 290 obtains the difference between the voltage detected by the detection terminal 291 and the voltage detected by the detection terminal 292, thereby detecting the bias voltage Vb between the potential of the plasma PL generated in the space 51 by the plasma generating unit 280 and the potential of the electrode 10, to which power is supplied, with satisfactory precision.

Alternatively, a case, as a comparative example, is considered where the plasma treatment apparatus 200 has no detecting unit 290, and a predetermined measurement tool is attached to the plasma treatment apparatus 200 at the time of maintenance to detect the bias voltage Vb. In this case, if the manufacturing of a semiconductor device using the plasma treatment apparatus 200 is not temporarily interrupted, the correcting unit 230 cannot perform correction so that the bias voltage Vb is substantially identical to the target value Vt. Accordingly, throughput in the method of manufacturing a semiconductor device tends to be degraded.

In contrast, in the third embodiment, the plasma treatment apparatus 200 includes the detecting unit 290. The detecting unit 290 detects the bias voltage Vb. Thus, the correcting unit 230 can perform correction so that the bias voltage Vb is substantially identical to the target value Vt, without interrupting the manufacturing a semiconductor device using the plasma treatment apparatus 200 (as inline processing). As a result, it is possible to suppress degradation in throughput in the method of manufacturing a semiconductor device.

It should be noted that, although in the third embodiment, a case has been described where the plasma treatment apparatus 200 is an inductive coupling plasma (ICP) RIE apparatus, the plasma treatment apparatus 200 is not limited to the ICP RIE apparatus. For example, the plasma treatment apparatus 200 may be an electron cycrotron resonance (ECR) RIE apparatus or a parallel flat plate RIE apparatus. When the plasma treatment apparatus 200 is a parallel flat plate RIE apparatus, the plasma generating unit 280 has an upper electrode which is arranged to face the electrode 10 inside the treatment chamber 50, instead of the antenna coil 282 and the dielectric wall 283.

Fourth Embodiment

Next, a plasma treatment apparatus 300 according to a fourth embodiment will be described with reference to FIGS. 10 and 11. FIG. 10 is a diagram showing the schematic configuration of the plasma treatment apparatus 300 according to the fourth embodiment. FIG. 11 is a diagram showing the internal configuration of a correcting unit 330.

Hereinafter, description will be provided focusing on differences from the third embodiment.

The plasma treatment apparatus 300 includes a power supply circuit 320, a plasma generating unit 280, a detecting unit 290, and a controller 360. The controller 360 manages a processing condition which is used in controlling the plasma generating unit 280. The power supply circuit 320 has the correcting unit 330. The correcting unit 330 receives a signal representing the processing condition from the controller 360.

Specifically, as shown in FIG. 11, the correcting unit 330 has a variable-capacitance unit 235, a storage unit 336, a determining unit 337, a comparing unit 333, and a changing unit 234.

The storage unit 336 stores a plurality of target values associated with the processing condition. The processing condition includes, for example, the type of a treatment gas which should be supplied to the treatment chamber 50 by the plasma generating unit 280. The storage unit 336 stores, for example, target value information shown in FIG. 12. The target value information includes a treatment gas column 3361 and a target value column 3362. The treatment gas column 3361 stores information regarding the type of a treatment gas, for example, “treatment gas A,” “treatment gas B,” . . . . The target value column 3362 stores information regarding a target value, for example, “Vta,” “Vtb,” . . . . By referring to the target value information, a target value corresponding to the type of a treatment gas can be specified. For example, by referring to the target value information, the target value corresponding to “treatment gas A” can be specified as “Vta,” and the target value corresponding to “treatment gas B” can be specified as “Vtb.” When a plurality of plasma treatment apparatuses 300 are activated under the same processing condition, the target value information stored in the storage unit 336 can be commonly used, and the storage unit 336 itself can be shared between the apparatuses.

The determining unit 337 receives a signal representing a processing condition from the controller 360. When the signal representing the processing condition is received, the determining unit 337 determines a target value corresponding to the processing condition represented by the signal by referring to the target value information stored in the storage unit 336. The determining unit 337 supplies the determined target value to the comparing unit 333.

The comparing unit 333 preferentially uses the target value supplied from the determining unit 337 over the target value Vt set in advance. That is, the comparing unit 333 compares the bias voltage Vb detected by the detecting unit 290 and the target value determined by the determining unit 337.

As shown in FIG. 13, a method of manufacturing a semiconductor device using the plasma treatment apparatus 300 is different from the third embodiment in the following respect.

In Step S41, the determining unit 337 determines whether or not the processing condition by the plasma treatment apparatus 300 is changed. For example, the determining unit 337 holds the signal representing the processing condition received from the controller 360, and when a signal representing a different processing condition is received, determines that the processing condition is changed. When a signal representing the same processing condition is received or when a signal representing a processing condition is not received, it is determined that the processing condition is not changed. When the processing condition is changed (‘Yes’ in Step S41), the determining unit 337 progresses the process to Step S42. When the processing condition is not changed (‘No’ in Step S41), the process ends.

In Step (determining step) S42, the determining unit 337 determines a target value corresponding to the processing condition represented by the signal by referring to the target value information stored in the storage unit 336. The determining unit 337 supplies the determined target value to the comparing unit 333. The comparing unit 333 changes the target value, which is used for comparison, to the target value supplied from the determining unit 337.

Then, in Step S35, at least one of the capacitance value of the variable-capacitance element 231 and the capacitance value of the variable-capacitance element 232 is changed in accordance with the comparison result in Step S34 so that the bias voltage Vb detected in Step S33 is substantially identical to the target value determined in Step S42. In Step S36, the controller 360 controls the plasma generating unit 280 under the processing condition being managed.

In this way, in the fourth embodiment, a target value is changed for each processing condition (for example, the type of a treatment gas). For this reason, the correcting unit 330 can perform correction so that the bias voltage Vb is substantially identical to a target value adjusted to the processing condition. As a result, it is possible to reduce a variation in the processing dimension between different plasma treatment apparatus under each processing condition.

Fifth Embodiment

Next, a plasma treatment apparatus 400 according to a fifth embodiment will be described with reference to FIG. 14. FIG. 14 is a diagram showing the internal configuration of a correcting unit 430 in the plasma treatment apparatus 400. Hereinafter, description will be provided focusing on differences from the third embodiment.

In the plasma treatment apparatus 400, the correcting unit 430 of a power supply circuit 420 further has a storage unit 436, a determining unit 437, and a timer 438.

The storage unit 436 stores a plurality of target values associated with intervals to which the elapsed time of plasma treatment belongs. The elapsed time refers to, for example, an elapsed time after a cleaning process inside the treatment chamber 50 is performed immediately before. The storage unit 436 stores, for example, target value information shown in FIG. 15. The target value information includes an elapsed time column 4361 and a target value column 4362. The elapsed time column 4361 stores information regarding an interval to which an elapsed time belongs, for example, “0 to T1,” “T1 to T2,” . . . . The target value column 4362 stores information regarding a target value, for example, “Vt1,” “Vt2,” . . .. By referring to the target value information, a target value corresponding to an interval to which the elapsed time belongs can be specified. For example, by referring to the target value information, the target value corresponding to “0 to T1” can be specified as “Vt1,” and the target value corresponding to “T1 to T2” can be specified as “Vt2.”

The determining unit 437 receives a signal representing cleaning inside the treatment chamber 50 being completed from the controller 360. When the signal representing the cleaning inside the treatment chamber 50 being completed is received, the determining unit 437 activates the timer 438. Thus, the timer 438 starts to count the elapsed time.

The determining unit 437 accesses the timer 438 to acquire information of the elapsed time from the timer 438. The determining unit 437 determines a target value corresponding to an interval to which the elapsed time belongs by referring to the target value information stored in the storage unit 436. The determining unit 437 supplies the determined target value to the comparing unit 333.

As shown in FIG. 16, a method of manufacturing a semiconductor device using the plasma treatment apparatus 400 is different from the third embodiment in the following respect.

In Step S51, the determining unit 437 determines whether or not the interval to which the elapsed time belongs is changed. For example, the determining unit 337 accesses the timer 438 to acquire information of the elapsed time from the timer 438. The determining unit 437 holds the signal representing the interval of the elapsed time corresponding to the target value used immediately before. When the elapsed time acquired from the timer 438 does not belong to the interval of the held elapsed time, the determining unit 437 determines that the interval to which the elapsed time belongs is changed. When the elapsed time acquired from the timer 438 belongs to the interval of the held elapsed time, it is determined that the interval to which the elapsed time belongs is not changed. When the interval to which the elapsed time belongs is changed (‘Yes’ in Step S51), the determining unit 437 progresses the process to Step S52. When the interval to which the elapsed time belongs is not changed (‘No’ in Step S51), the process progresses to Step S32.

In Step S52, the determining unit 437 determines a target value corresponding to the interval to which the elapsed time belongs by referring to the target value information stored in the storage unit 436. The determining unit 437 supplies the determined target value to the comparing unit 333. The comparing unit 333 changes the target value, which is used for comparison, to the target value supplied from the determining unit 437.

Then, in Step S35, at least one of the capacitance value of the variable-capacitance element 231 and the capacitance value of the variable-capacitance element 232 is changed in accordance with the comparison result in Step S34 so that the bias voltage Vb detected in Step S33 is substantially identical to the target value determined in Step S52.

In this way, in the fifth embodiment, the target value is changed for each interval to which the elapsed time belongs. For this reason, the correcting unit 430 can perform correction so that the bias voltage Vb is substantially identical to a target value adjusted to the interval to which the elapsed time belongs. As a result, it is possible to reduce a variation in the processing dimension between different plasma treatment apparatuses while taking into consideration a time-dependent state change inside the treatment chamber 50.

Sixth Embodiment

Next, a plasma treatment apparatus 500 according to a sixth embodiment will be described with reference to FIG. 17. FIG. 17 is a diagram showing the schematic configuration of the plasma treatment apparatus 500 according to the sixth embodiment. Hereinafter, description will be provided focusing on differences from the third embodiment.

The plasma treatment apparatus 500 further includes a storage unit 570 and a controller 560.

The storage unit 570 stores correlation information regarding a correlation between a bias voltage and a processing shift amount. The processing shift amount is, for example, a shift amount in the actual processing dimension from an etching mask pattern. The storage unit 570 stores, for example, correlation information such as shown in FIG. 18. FIG. 18 shows the actual evaluation result of a correlation between a bias voltage and a processing shift amount, and it can be understood that the bias voltage and a processing shift amount has approximately a correlation along a straight line indicated by a one-dot-chain line. By referring to this correlation information, a processing shift amount corresponding to a current bias voltage can be predicted. For example, by referring to the correlation information, it can be estimated that a processing shift amount corresponding to a bias voltage Vb11 is L11.

The controller 560 receives the bias voltage Vb detected by the detecting unit 290 from the detecting unit 290. The controller 560 predicts a processing shift amount corresponding to the bias voltage Vb detected by the detecting unit 290 by referring to the correlation information stored in the storage unit 570. The controller 560 adjusts the processing condition on the basis of the predicted processing shift amount so that the processing shift amount falls within the range of a predetermined threshold value. The processing condition which should be adjusted includes, for example, a processing time. When the predicted processing shift amount exceeds the range of the predetermined threshold value, the controller 560 changes the processing time so that the processing shift amount falls within the range of the predetermined threshold value.

As shown in FIG. 19, a method of manufacturing a semiconductor device using the plasma treatment apparatus 500 is different from the third embodiment in the following respect.

In Step S61, the comparing unit 233 of the power supply circuit 220 compares the bias voltage Vb represented by the signal received from the detecting unit 290 with the target value Vt, and supplies the comparison result to the changing unit 234. The changing unit 234 determines whether or not the bias voltage Vb detected by the detecting unit 290 is substantially identical to the target value Vt in accordance with the supplied comparison result. When the bias voltage Vb is not substantially identical to the target value Vt (‘No’ in Step S61), the changing unit 234 progresses the process to Step S62. When the bias voltage Vb is substantially identical to the target value Vt (‘Yes’ in Step S61), the process progresses to Step S36.

In Step S62, the changing unit 234 of the power supply circuit 220 determines whether or not the number of times in which the bias voltage Vb is not substantially identical to the target value Vt is equal to or greater than a predetermined number of times. Specifically, the changing unit 234 holds the count value of the number of times in which the bias voltage Vb is not substantially identical to the target value Vt, and counts up the count value of the number of times. The changing unit 234 compares the count value after counting up with the predetermined number of times, and when the count value is equal to or greater than the predetermined number of times (‘Yes’ in Step S62), progresses the process to Step S63. When the count value is smaller than the predetermined number of times (‘No’ in Step S62), the process progresses to Step S35.

In Step S63, the changing unit 234 of the power supply circuit 220 supplies a signal representing the number of times, in which the bias voltage Vb is not substantially identical to the target value Vt, being equal to or greater than the predetermined number of times to the controller 560. When the signal is received, the controller 560 receives the bias voltage Vb detected by the detecting unit 290 from the detecting unit 290. The controller 560 predicts a processing shift amount corresponding to the bias voltage Vb detected by the detecting unit 290 by referring to the correlation information stored in the storage unit 570.

In Step S64, the controller 560 adjusts the processing condition on the basis of the predicted processing shift amount so that the processing shift amount falls within the range of a predetermined threshold value. The processing condition which should be adjusted includes, for example, a processing time. When the predicted processing shift amount exceeds the range of the predetermined threshold value, the controller 560 changes the processing time so that the processing shift amount falls within the range of the predetermined threshold value.

In this way, in the sixth embodiment, a feedback operation which includes the operation of the detecting unit 290 to detect the bias voltage Vb and the operation of the correcting unit 230 to correct the capacitance value of the power supply circuit 220 is performed a predetermined number of times or more, if the bias voltage Vb is not substantially identical to the target value Vt, a processing shift amount corresponding to the detected bias voltage Vb is predicted, and the processing condition is adjusted on the basis of the predicted processing shift amount so that the processing shift amount falls within a predetermined allowable range. Therefore, even when the bias voltage Vb is not substantially identical to the target value Vt, it is possible to reduce a variation in the processing dimension between different plasma treatment apparatuses.

While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions. 

1. A plasma treatment apparatus comprising: an electrode which is arranged inside a treatment chamber and on which a substrate to be treated is placed; a first power supply circuit which supplies power to the electrode; a plasma generating unit which generates plasma in a space separated from the electrode inside the treatment chamber; a second power supply circuit which supplies power to the plasma generating unit; a sensing unit which senses a parameter output from the first power supply circuit; and a control unit which controls power supplied from the second power supply circuit so that the parameter sensed by the sensing unit becomes close to or substantially equal to a target value.
 2. The plasma treatment apparatus according to claim 1, wherein the parameter sensed by the sensing unit includes a voltage.
 3. The plasma treatment apparatus according to claim 2, wherein the control unit increases power supplied from the second power supply circuit when the voltage sensed by the sensing unit is higher than the target value and decreases power supplied from the second power supply circuit when the voltage sensed by the sensing unit is lower than the target value.
 4. The plasma treatment apparatus according to claim 1, wherein the parameter sensed by the sensing unit includes a current.
 5. The plasma treatment apparatus according to claim 4, wherein the control unit decreases power supplied from the second power supply circuit when the current sensed by the sensing unit is greater than the target value and increases power supplied from the second power supply circuit when the current sensed by the sensing unit is smaller than the target value.
 6. The plasma treatment apparatus according to claim 1, wherein the first power supply circuit includes a generating unit which generates power, a second sensing unit which senses power generated by the generating unit, and a second control unit which controls power generated by the generating unit in accordance with the sensing result of the second sensing unit, a control operation of the control unit and a control operation of the second control unit being performed in parallel in a mutually independent form.
 7. A plasma treatment method in a plasma treatment apparatus that includes an electrode, a first power supply circuit, a plasma generating unit, and a second power supply circuit, the electrode being arranged inside a treatment chamber and on the electrode a substrate to be treated being placed, the first power supply circuit supplying power to the electrode, the plasma generating unit generating plasma in a space separated from the electrode inside the treatment chamber, the second power supply circuit supplying power to the plasma generating unit, the plasma treatment method comprising: sensing a parameter output from the first power supply circuit; and controlling power supplied from the second power supply circuit so that the sensed parameter becomes close to or substantially equal to a target value.
 8. The plasma treatment method according to claim 7, wherein, in the sensing of the parameter, a voltage output from the first power supply circuit is sensed, and in the controlling of power, when the sensed voltage is higher than the target value, power supplied from the second power supply circuit increases, and when the sensed voltage is lower than the target value, power supplied from the second power supply circuit decreases.
 9. The plasma treatment method according to claim 7, wherein, in the sensing of the parameter, a current output from the first power supply circuit is sensed, and in the controlling of power, when the sensed current is greater than the target value, power supplied from the second power supply circuit decreases, and when the sensed current is smaller than the target value, power supplied from the second power supply circuit increases.
 10. A plasma treatment apparatus comprising: an electrode which is arranged inside a treatment chamber and on which a substrate to be treated is placed; a power supply circuit which supplies power to the electrode; a plasma generating unit which generates plasma in a space separated from the electrode inside the treatment chamber; and a detecting unit which detects a bias voltage that is a difference between a potential of the plasma generated by the plasma generating unit and a potential of the electrode to which power is supplied from the power supply circuit, wherein the power supply circuit includes a main unit which generates power to be supplied to the electrode, and a correcting unit which corrects a capacitance value of the power supply circuit so that the bias voltage detected by the detecting unit becomes close to or substantially equal to a target value.
 11. The plasma treatment apparatus according to claim 10, wherein the detecting unit includes a first detection terminal which extends to the space separated from the electrode inside the treatment chamber, and a second detection terminal which is electrically connected to the electrode, and wherein the detecting unit obtains a difference between a voltage detected by the first detection terminal and a voltage detected by the second detection terminal to detect the bias voltage.
 12. The plasma treatment apparatus according to claim 10, wherein the correcting unit includes a first variable-capacitance element which is connected in series with the main unit with respect to the electrode, a second variable-capacitance element which is connected in parallel with the main unit with respect to the electrode, and a changing unit which changes at least one of a capacitance value of the first variable-capacitance element and a capacitance value of the second variable-capacitance element so that the bias voltage detected by the detecting unit becomes close to or substantially equal to the target value.
 13. The plasma treatment apparatus according to claim 12, wherein the changing unit performs at least an operation to increase the capacitance value of the second variable-capacitance element when the bias voltage detected by the detecting unit is higher than the target value and performs at least an operation to increase the capacitance value of the first variable-capacitance element when the bias voltage detected by the detecting unit is lower than the target value.
 14. The plasma treatment apparatus according to claim 10, wherein the correcting unit includes a storage unit which stores a plurality of different target values, and a determining unit which determines a target value corresponding to a processing condition of plasma treatment from among the plurality of different target values stored in the storage unit, the capacitance value of the power supply circuit being corrected so that the bias voltage detected by the detecting unit becomes close to or substantially equal to the target value determined by the determining unit.
 15. The plasma treatment apparatus according to claim 10, wherein the correcting unit includes a storage unit which stores a plurality of different target values, and a determining unit which determines a target value corresponding to an elapsed time of plasma treatment from among the plurality of different target values stored in the storage unit, the capacitance value of the power supply circuit being corrected so that the bias voltage detected by the detecting unit becomes close to or substantially equal to the target value determined by the determining unit.
 16. The plasma treatment apparatus according to claim 10, further comprising: a storage unit which stores correlation information regarding a correlation between the bias voltage and a processing shift amount; and a controller which predicts the processing shift amount on the basis of the bias voltage detected by the detecting unit and the correlation information stored in the storage unit, and adjusts a processing condition so that the processing shift amount falls within a range of a threshold value.
 17. A plasma treatment method in a plasma treatment apparatus that includes an electrode and a power supply circuit, the electrode being arranged inside a treatment chamber, and on the electrode a substrate to be treated being placed, the power supply circuit supplying power to the electrode, the plasma treatment method comprising: supplying power from the power supply circuit to the electrode and generating plasma in a space separated from the electrode inside the treatment chamber; detecting a bias voltage that is a difference between the potential of the generated plasma and the potential of the electrode to which power is supplied; correcting a capacitance value of the power supply circuit so that the detected bias voltage becomes close to or substantially equal to a target value; and processing the substrate to be treated using the plasma treatment apparatus after the correcting is performed.
 18. The plasma treatment method according to claim 17, wherein the power supply circuit includes a main unit which generates power to be supplied to the electrode, and a correcting unit which compensates for a capacitance value of the main unit to correct the capacitance value of the power supply circuit so that the detected bias voltage becomes close to or substantially equal to the target value, wherein the correcting unit includes a first variable-capacitance element which is connected in series with the main unit with respect to the electrode, and a second variable-capacitance element which is connected in parallel with the main unit with respect to the electrode, and wherein, in the correcting of the capacitance value of the power supply circuit, at least one of a capacitance value of the first variable-capacitance element and a capacitance value of the second variable-capacitance element is changed so that the detected bias voltage becomes close to or substantially equal to the target value.
 19. The plasma treatment method according to claim 17, further comprising: determining a target value corresponding to a processing condition of plasma treatment from among a plurality of different target values, and comparing the detected bias voltage with the determined target value before the correcting of the capacitance value of the power supply circuit, wherein the capacitance value of the power supply circuit is corrected in accordance with the comparison result so that the detected bias voltage becomes close to or substantially equal to the determined target value.
 20. The plasma treatment method according to claim 17, further comprising: determining a target value corresponding to an elapsed time of plasma treatment from among a plurality of different target values, and comparing the detected bias voltage with the determined target value before the correcting of the capacitance value of the power supply circuit, wherein the capacitance value of the power supply circuit is corrected in accordance with the comparison result so that the detected bias voltage becomes close to or substantially equal to the determined target value. 